The present invention relates to a golf ball material which includes an ionomer blend composition containing a polysilsesquioxane. The invention also relates to a golf ball in which such a golf ball material is used, and to a method for preparing such a golf ball material.
Ionomeric resins (ionomers) are useful materials in golf balls, among other things. Ionomers obtained by using metal cations to neutralize copolymers of an α-olefin such as ethylene with an unsaturated carboxylic acid such as acrylic acid (AA), methacrylic acid (MAA) or maleic acid, and terpolymers of such an α-olefin and unsaturated carboxylic acid with an ester (softening monomer) of any of these unsaturated carboxylic acids, are especially useful as golf ball materials.
Golf balls manufactured using ionomer-based materials generally include various fillers for different purposes. Fillers such as titanium oxide, barium sulfate and calcium carbonate are used for such purposes as to increase coloration (whitening), specific gravity control or hardness enhancement. Various silicone materials are used for such purposes as to improve heat resistance, optical properties or dimensional stability of golf balls. With regard to silicone materials, the use of polyorganosiloxanes having a dialkylsiloxane skeleton is disclosed in, for example, JP-A 2005-74100 (Patent Document 1), JP-A 2002-511283 (Patent Document 2) and JP-A 2002-514109 (Patent Document 3).
In recent years, use has come to be made of polysilsesquioxane-type organic silicone materials having, unlike the foregoing polyorganosiloxane-type polymer structure, a steric structure prepared from a polyfunctional organosilane such as an organotrichlorosilane or an organotrialkoxysilane as the starting material. U.S. Pat. No. 7,208,546 (Patent Document 4) and U.S. Pat. No. 6,585,607 (Patent Document 5) mention golf ball materials which use Polyhedral Oligomeric Silsesquioxane (POSS) commercially sold by Hybrid Plastics (U.S.).
Research has recently been reported on polyphenylsilsesquioxane (PPSQ) and polymethylsilsesquioxane (PMSQ), which are novel materials having higher molecular weights than the above POSS moiety. For example, reference may be made to “Rheological properties of poly(methyl methacrylate)(PMMA)/rigid ladderlike polyphenylsilsesquioxane (PPSQ)” in Journal of Applied Polymer Science, 104 (1), 352-359 (2007) (Non-Patent Document 1), and to “Siloxane surfactant-modified clay and its effect in reinforcing the laminate of polymethylsilsesquioxane” in Journal of Applied Polymer Science, 100 (5), 3974-3980 (2006) (Non-Patent Document).
The above polysilsesquioxane materials having at least a three-dimensional structure are basically organic-inorganic hybrid materials. It is thus expected that, depending on how they are used, such polysilsesquioxane materials will function as an inorganic filler in ionomer-based golf ball materials and will at the same time provide the resin modifying role of an organic silicone. However, the use of polysilsesquioxane materials to impart both roles of a filler and a resin modifier in the above-mentioned ionomeric golf ball materials has not been reported yet in the past literatures and patents.
Patent Document 1:JP-A 2005-074100Patent Document 2:JP-A 2002-511283Patent Document 3:JP-A 2002-514109Patent Document 4:U.S. Pat. No. 7,208,546Patent Document 5:U.S. Pat. No. 6,585,607Non-Patent Document 1:Journal off Applied PolymerScience, 104 (1), 352-359(2007)Non-Patent Document 2:Journal off Applied PolymerScience, 100 (5), 3974-3980(2006)